It is, of course, generally known to measure rail cant of parallel adjacent rails in a railway. Rail cant is measured relative to the plane established by the top of the adjacent rails in track. Rail is typically installed in track on an inward inclination of 1:40 (1.43 degrees) for the purpose of best wheel-to-rail contact. Over time, track degrades because of train loadings, and thus the inclination of the rail readily changes due to various causes stemming from said loadings. In other words, rail cant can change, either inward or outward with the passing of train traffic.
Track measurement vehicles, known as geometry cars, commonly measure existing rail cant and have capability to identify variation from design. These geometry cars use optical measurement systems that have been calibrated to report rail cant accurately. Rail cant exceptions (variation from design beyond defined thresholds) are reported by location and magnitude so that track repair crews can make maintenance corrections.
Track measurement crews need rugged, easy to use measurement tools to manually measure track and rail condition as they do their maintenance work. No tool currently exists to measure rail cant (relative to top of track plane). Therefore, track crews do not have a simple and accurate means to confirm rail cant variation or design exceptions.
The rail cant measurement tool according the present specifications is designed to provide accurate measurement of existing rail cant, as summarized in more detail hereinafter.